Cone Beam CT: Slice thickness

Cone beam CT units have a range of slice thicknesses available.  Most units fall between 0.1 mm to 0.4 mm slice thickness.  There are units with smaller slice thickness available, however I am focusing on the 0.1 to 0.4 mm range for this post.  The first thing to understand is what you are changing when you change the slice thickness.  As a cone beam CT dataset is a volume of data, the slice thickness is directly associated with the voxel size.  A voxel is a 3D ‘box’ of data.  In a 2D image the corresponding data is a pixel. Below is an example of a dataset with a single voxel noted in green.

The basic understanding for voxel size (slice thickness) and spatial resolution is that the smaller the voxel size = greater (or higher) spatial resolution.  So this would mean a slice thickness of 0.1 mm will provide a higher spatial resolution versus a slice thickness of 0.4 mm.  One issue with a smaller slice thickness is that to achieve this it requires more radiation than a larger slice thickness.  While using a small slice thickness for increased spatial resolution sounds great in theory, as of now (current research), a 0.3 mm slice will provide the same diagnostic ability as a 0.1 mm slice.

I realize that this information is constantly changing and manufacturers are improving units and software and this may change over time.  The reason I have excluded the very small slice thickness is due to a lack of research.  If I have missed a paper somewhere, please let me know so that I can add to this post.

Thanks and enjoy!

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